The serine/threonine kinase cdk-2 is essential for normal cellular cycling and plays a critical role in disorders arising from abnormal cell cycling, a common characteristic of many oncological disorders. Inhibitors of cdk-2 are therefore useful in the treatment of various types of cancers and other diseases or conditions related to abnormal cell growth. See, for example, Meijer, et al., Pharmacol. and Therapeutics, 82 (2-3), 279-284 (1999), Sausville, et al., Pharmacol. and Therapeutics, 82 (2-3), 285-292 (1999). The serine/threonine kinase cdk-5, along with its cofactor p25, or the longer cofactor p35, has been linked to neurodegenerative disorders, and inhibitors of cdk-5 are therefore useful in the treatment of disorders such as Alzheimer's Disease, Parkinson's Disease, stroke, and Huntington's Disease. Treatment of such neurodegenerative disorders using cdk-5 inhibitors is supported by the finding that cdk-5 is involved in the phosphorylation of tau protein, and dopamine and cyclic AMP-regulated phosphoprotein (DARPP-32) at threonine 75, and is thus indicated as playing a role in dopaminergic transmission.
Glycogen synthase kinase-3 (GSK-3), a proline-directed, serine/threonine kinase for which two isoforms, GSK-3α and GSK-30β, have been identified, phosphorylates the rate-limiting enzyme of glycogen synthesis, glycogen synthase (GS). See, for example, Embi, et al., Eur. J. Biochem., 107, 519-527 (1980). GSK-3α and GSK-3β are both highly expressed in the body. See, for example, Woodgett, et al., EMBO, 9, 2431-2438 (1990) and Loy, et al., J. Peptide Res., 54, 85-91 (1999). Besides GS, a number of other GSK-3 substrates have been identified, including many metabolic, signaling, and structural proteins. Notable among the plurality of signaling proteins regulated by GSK-3 are many transcription factors, including activator protein-1; cyclic AMP response element binding protein (CREB); the nuclear factor (NF) of activated T-cells; heat shock factor-1; β-catenin; c-Jun; c-Myc; c-Myb; and NF-KB. See, for example, C. A. Grimes, et al., Prog. Neurobiol., 65, 391-426 (2001), H. Eldar-Finkelman, Trends in Molecular Medicine, 8, 126-132 (2002), and P. Cohen, et al., Nature, 2, 1-8, (2001). Accordingly, targeting the activity of GSK-3 has significant therapeutic potential in the treatment of many disparate pathologies and conditions, for example, Alzheimer's Disease (A. Castro, et al., Exp. Opin. Ther. Pat., 10, 1519-1527 (2000)); asthma (P. J. Barnes, Ann. Rev. Pharmacol. Toxicol., 42, 81-98 (2002)); cancer (Beals, et al., Science, 275, 1930-1933 (1997), L. Kim, et al., Curr. Opin. Genet. Dev., 10, 508-514 (2000), and Q. Eastman, et al., Curr. Opin. Cell Biol., 11, 233 (1999)); diabetes and its related sequelae, for example, Syndrome X and obesity (S. E. Nikoulina, et al., Diabetes, 51, 2190-2198 (2002), Orena, et al., JBC, 15765-15772 (2000), and Summers, et al., J. Biol. Chem., 274, 17934-17940 (1999)); hair loss (S. E. Millar, et al., Dev. Biol., 207, 133-149 (1999) and E. Fuchs, et al., Dev. Cell, 1, 13-25 (2001)); inflammation (P. Cohen, Eur. J. Biochem., 268, 5001-5010 (2001)); mood disorders, such as depression (A. Adnan, et al., Chem. Rev., 101, 2527-2540 (2001) and R. S. B. Williams, et al., Trends Phamacol. Sci., 21, 61-64 (2000)); neuronal cell death and stroke (D. A. E. Cross, et al., J. Neurochem., 77, 94-102 (2001) and C. Sasaki, et al., Neurol. Res., 23, 588-592 (2001)); bipolar disorder (Klein, et al., PNAS, 93, 8455-8459 (1996)); skeletal muscle atrophy (G. J. Brunn, et al., Science, 277, 99-101 (1997), R. E. Rhoads, J. Biol. Chem., 274, 30337-30340 (1999), V. R. Dharmesh, et al., Am. J. Physiol. Cell Physiol. 283, C545-551 (2002), and K. Baar, et al., A. J. Physiol., 276, C120-C127 (1999)); decreased sperm motility (Vijayaraghavan, et al., Biol. Reproduction, 54, 709-718 (1996)); and in cardio-protection (C. Badorff, et al., J. Clin. Invest., 109, 373-381 (2002), S. Haq, et al., J. Cell Biol., 151, 117-129 (2000), and H. Tong, et al., Circulation Res., 90, 377-379 (2002)).
Certain pyrazole derivatives of formula (II),
useful as inhibitors of cdk2, cdk5, and GSK-3, are disclosed in commonly-assigned PCT International Application Publication No. WO 02/18346, wherein R1, R2, R3, and R4 are as defined therein.